Impact of vitamin C and vitamin C nanoparticles on testicular blood flow, semen parameters, circulating testosterone, and testicular histopathological findings of mature goat bucks during stressed summer conditions.

The present study investigated the effects of vitamin C and its nanoparticles (NPs) on testicular hemodynamics, semen parameters, and oxidative status in mature Baladi goat bucks under heat-stress conditions. Fifteen bucks were divided into 3 groups (5 /each): the control group was administered subcutaneous (S/C) injections of 1 ml of corn oil, the vitamin C group was S/C injected with 1 ml of traditional vitamin C (5 mg/kg body weight), and the vitamin C NPs group was received S/C injections of 1 ml of vitamin C NPs (1.25 mg/kg body weight). All groups received injections twice/week at 3–4-day intervals for four consecutive weeks. Testicular blood flow (TBF) was assessed using Doppler ultrasonography, while testicular volume (TV) and echotexture (PIX) were evaluated by B-mode ultrasonography and computer-assisted image analysis software. Serum testosterone (T), nitric oxide (NO), and total antioxidant capacity (TAC) were measured using commercial kits. Semen samples were collected using an electroejaculator at 3–4-day intervals throughout the experimental period and again 2 months after the final injection to evaluate long-term effects. Testicular tissues were examined histopathologically. Results revealed a marked increase in TBF, indicated by significant decreases (P ˂ 0.05) in Doppler indices in both treated groups compared to the control. Vitamin C NPs and vitamin C groups showed higher T, NO, and TAC levels (P < 0.05) compared to the control. However, the vitamin C NPs group showed a noticeable reduction in TV, PIX, and all semen quality parameters compared to the other groups. Histopathological examination showed small-sized, atrophied seminiferous tubules lined by few spermatogenic cells and loss of spermatids in the vitamin C NPs group. Conversely, the vitamin C group exhibited improved semen characteristics, with PIX and most semen parameters exceeding both other groups (P < 0.05). Although the negative effect of vitamin C NPs on semen quality was reversed 2 months after the last administration, the findings highlighted potential risks associated with nanoparticle administration. In conclusion, vitamin C NPs improved testicular vascularization and antioxidant status, but they temporarily impaired semen quality and testicular structure. While vitamin C enhances testicular function and semen parameters, its use could be recommended to improve the reproductive performance of bucks under HS conditions. Additional research may be needed to refine the optimal dosage, formulation, and administration schedule of the nanoparticles to enhance efficacy and mitigate adverse effects.